Composite flat membrane brittle fracture device and brittle fracture method

Abstract

The present invention discloses a composite flat membrane brittle fracture device and a brittle fracture method, wherein a composite flat membrane brittle fracture device processes a flat membrane material into a slender strip; places the strip flat membrane into the brittle fracture device and fixes and clamps it; puts the device and the sample into a coolant to fully cool them; takes out the brittle fracture device, applies stress in the vertical and horizontal directions to the flat membrane in turn, so that the flat membrane breaks; and finally obtains a brittle-fractured composite flat membrane sample. This method uses the brittle fracture device to limit the movement of the flat membrane and reduce the difficulty of operation. The sample obtained by this method has a smooth cross-section and is not easy to damage the surface layer. Therefore, when used for observation with a scanning microscope, a clear image can be obtained, and the image is rich in details and closer to the actual situation, overcoming the problems of the traditional brittle fracture method that cannot completely separate the composite layer, the uneven cross-section, the damage of the contamination layer, and the low success rate of manual operation.

Description

Technical Field

[0001] The invention provides a composite flat membrane brittle fracture device and a brittle fracture method, mainly relating to the field of sample preparation using a scanning electron microscope, and in particular to a composite flat membrane material sample brittle fracture device and a brittle fracture method. Background Art

[0002] In scientific research, it is often necessary to use a scanning electron microscope to observe the in-situ morphology of a flat membrane cross section in order to observe membrane fouling or membrane modification characteristics.

[0003] The common cross-section preparation method usually uses the low temperature of liquid nitrogen to make the material brittle, and then manually bends the membrane material using tweezers to obtain the cross-section sample. However, flat membranes are mostly composite materials, such as Figure 1 As shown, the composite flat membrane generally includes a membrane pollution layer 13, a membrane skin layer 14, a membrane pore layer 15, and a membrane support layer 16. In particular, the composite flat membrane using non-woven fabric as the support material has the characteristics of soft material and strong toughness, and is difficult to be disconnected by manpower; while the upper pollution layer and the membrane surface skin layer are relatively fragile and easily deformed by external forces, which will affect the observation effect.

[0004] In order to break the composite flat membrane material and prepare the cross section, the composite flat membrane material is often broken by shearing or multiple tearing, which will cause the structure of the cross section to change, destroy the original morphology of the cross section, and affect the observation effect. The traditional manual method has the following problems. First, the cross section is not flat enough, which is not conducive to observation; secondly, it is difficult to operate small-sized flat membrane samples manually, and the preparation success rate is low; at the same time, the non-woven fabric in the composite material is very tough. Even if it has been made brittle by liquid nitrogen, it is difficult to break it intact by human labor. Using a knife will contaminate the sample and destroy the original structure.

[0005] After cooling the composite flat membrane sample in liquid nitrogen, take it out and cut the sample with scissors to obtain Figure 2 The SEM image of the cross section of the flat membrane shown shows that the cross section has been damaged by extrusion, the structures of the various layers are intertwined, and the structure of the cross section cannot be observed.

[0006] Scratch the back of the sample with a scalpel, cool the sample in liquid nitrogen, and then use tweezers to clamp both ends of the sample for brittle fracture. Figure 3 The cross-sectional SEM image of the flat membrane is shown. It can be seen that the non-woven fabric layer is cut, the membrane pore layer has been damaged by pressure during cutting, and the contamination layer is in contact with the sample stage when the back is scratched, and is easy to adhere and fall off, so the complete cross-sectional structure of the composite flat membrane cannot be observed.

[0007] The samples were embedded in paraffin at room temperature and then sliced. Figure 4The cross-sectional SEM image of the flat membrane is shown. It can be seen that the membrane layer near the cross section collapses downward due to the traction force during slicing, especially the polymer material in the membrane pore layer is stretched and pulled, making it impossible to observe the actual cross-sectional situation.

[0008] Regarding the brittle fracture of polymer and film samples, the invention patent with the authorization number CN211478116 mentions a brittle fracture device. However, if the device is applied to a composite flat membrane, when the wedge-shaped impact rod impacts the flat membrane, due to the strong toughness of the flat membrane composite material, the flat membrane will undergo plastic deformation, affecting the observation effect. This method is more suitable for materials that can be directly broken by brittle fracture. The invention patent with the authorization number CN105699167B mentions a method of using silicon wafers for fixation and stress amplification. However, when the silicon wafer is fixed with a clamp, it will contact the surface of the flat membrane and exert force, which will affect the in-situ appearance of the contamination layer. It is suitable for situations where the material surface is relatively stable.

[0009] Therefore, in response to the above-mentioned technical problems, it is urgently necessary to develop a brittle fracture device and brittle fracture method for composite flat membrane materials that can control the cross-section direction and protect the in-situ morphology of the surface layer, which can solve the current difficulties in the preparation of composite flat membrane cross-sections and promote the development of membrane research. Summary of the invention

[0010] The present invention proposes a composite flat membrane brittle fracture method which is simpler to operate, has a higher success rate, and retains a more complete in-situ appearance of the brittle fracture surface. It can improve the precision and accuracy of manual operation and greatly improve the success rate of brittle fracture. It provides a composite flat membrane brittle fracture device and brittle fracture method.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A composite flat membrane brittle fracture device, suitable for brittle fracture of composite flat membranes, comprises a front guide plate and a rear guide plate, a horizontally arranged clamping mechanism is arranged between the front guide plate and the rear guide plate, the clamping mechanism comprises a fixed clamping device and a movable clamping device; the fixed clamping device is connected to the front guide plate and the rear guide plate through a fixed bolt, the front guide plate and the rear guide plate are both provided with a penetrating movable groove, the movable clamping device is arranged in the movable groove between the front guide plate and the rear guide plate through a movable bolt; the two ends of the composite flat membrane are respectively fixed in the fixed clamping device and the movable clamping device, by moving the movable clamping device, the movable bolt connected to the movable clamping device moves in the movable groove of the front guide plate and the rear guide plate, thereby realizing the brittle fracture of the composite flat membrane.

[0013] Preferably, the fixing clamping device comprises an upper membrane fixing clamping plate and a lower membrane fixing clamping plate, and the upper membrane fixing clamping plate and the lower membrane fixing clamping plate are locked and connected by a fixed end clamping component; the end of the composite flat membrane is arranged between the upper membrane fixing clamping plate and the lower membrane fixing clamping plate and the upper membrane fixing clamping plate and the lower membrane fixing clamping plate are locked by the fixed end clamping component.

[0014] The movable clamping device comprises a movable upper membrane clamping plate and a movable lower membrane clamping plate, and the movable upper membrane clamping plate and the movable lower membrane clamping plate are locked and connected by a movable end clamping component; the end of the composite flat membrane is arranged between the movable upper membrane clamping plate and the movable lower membrane clamping plate and the movable upper membrane clamping plate and the movable lower membrane clamping plate are locked by the movable end clamping component.

[0015] Preferably, a film placement area is provided between the fixed clamping device and the movable clamping device, the composite flat membrane is placed in the film placement area, and two ends of the composite flat membrane are respectively fixed in the fixed clamping device and the movable clamping device.

[0016] Preferably, the movable grooves on the front guide rail plate and the rear guide rail plate adopt an inverted L-shaped through-guide rail structure.

[0017] Preferably, the inverted L-shaped through guide rail structure with the movable groove adopts a vertical guide rail to connect the horizontal guide rail, and the vertical guide rail adopts an arc-shaped transition to the horizontal guide rail; the movable clamping device is slidably set on the top of the vertical guide rail in the movable groove of the front guide rail plate and the rear guide rail plate through a movable bolt.

[0018] The present invention also provides a composite flat membrane brittle fracture method, comprising the following steps:

[0019] S1: Process the composite flat membrane material into a long and thin strip, the width of which is slightly smaller than the width of the membrane placement area, and the processed length of the composite flat membrane material is slightly smaller than the length of the brittle fracture device;

[0020] S2: Place the composite flat membrane with the membrane pollution layer facing upwards above the membrane placement area, place one end of the composite flat membrane between the membrane fixed upper clamping plate and the membrane fixed lower clamping plate of the fixed clamping device in the brittle fracture device, and clamp it with the fixed end clamping component; place the other end of the composite flat membrane between the membrane movable upper clamping plate and the membrane movable lower clamping plate of the movable clamping device in the brittle fracture device, and clamp it with the movable end clamping component; fix the fixed clamping device between the front guide plate and the rear guide plate by a fixing bolt, and slide the movable clamping device on the top of the movable groove of the inverted L-shaped through-guide rail of the front guide plate and the rear guide plate by a movable bolt, so that the movable clamping device can move in the plane direction between the front guide plate and the rear guide plate, but is fixed in the direction perpendicular to the plane of the guide plate;

[0021] S3: immersing the composite flat membrane and the brittle fracture device as a whole in a cooling liquid to fully cool them;

[0022] S4: operate the brittle breaking device: place the brittle breaking device on a horizontal plane, apply operating force to the movable clamping device, and the movable clamping device moves in the movable groove guide rail of the inverted L-shaped structure through the movable bolt;

[0023] S5: causing the frozen flat membrane material to fracture brittlely, thereby obtaining a brittle fracture flat membrane material sample, and the section above the membrane-setting area relative to the membrane fixing clamp is the obtained clean section.

[0024] Preferably, the coolant used in step S3 is liquid nitrogen.

[0025] Preferably, the cooling time of the composite flat membrane in the cooling liquid in step S4 is not less than seconds.

[0026] Preferably, in step S4, a rotational operating force and a horizontal operating force are applied in sequence according to the direction of the guide rail by a brittle breaking device.

[0027] The present invention processes the flat membrane material into a long and thin strip; places the strip flat membrane into a brittle fracture device and fixes and clamps it; puts the device and the sample into a coolant to fully cool them; takes out the brittle fracture device, applies stress in the vertical and horizontal directions to the flat membrane in turn, so that the flat membrane breaks; and finally obtains a brittle-fractured composite flat membrane sample. This method uses the brittle fracture device to limit the movement of the flat membrane and reduce the difficulty of operation. The sample obtained by this method has a smooth cross-section and is not easy to damage the surface layer. Therefore, when used for scanning microscope observation, a clear image can be obtained, and the image is rich in details and closer to the actual situation. It overcomes the problems of the traditional brittle fracture method that the composite layer cannot be completely separated, the cross-section is uneven, the contamination layer is damaged, and the success rate of manual operation is low.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The problem of uneven force and difficulty in applying force in manual operation can be solved by designing a reasonable device, which is convenient for operation, improves the operation efficiency, and overcomes the problems of low preparation efficiency and low preparation success rate.

[0030] (2) Compared with other existing methods, this method retains the surface properties and in-situ appearance of the cross section to the greatest extent, which facilitates scanning electron microscopy observation of the cross section and reflects the actual structural characteristics of the composite flat membrane material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the layer structure of the composite flat membrane;

[0032] Figure 2 This is a SEM image of a flat film cross section obtained by a shearing method in a common method in the prior art;

[0033] Figure 3 This is a SEM image of a flat film cross section obtained by a wedge impact method in the prior art;

[0034] Figure 4 This is a SEM image of a flat membrane cross section obtained by the embedding section method in the prior art;

[0035] Figure 5 A schematic diagram of the three-dimensional structure of a composite flat membrane brittle fracture device proposed by the present invention;

[0036] Figure 6 This is a schematic diagram of the front view of a composite flat membrane brittle fracture device proposed by the present invention;

[0037] Figure 7 The operating direction of the composite flat membrane brittle fracture device proposed by the present invention is shown in FIG. Figure 1 ;

[0038] Figure 8 The operating direction of the composite flat membrane brittle fracture device proposed by the present invention is shown in FIG. Figure 2 ;

[0039] Fig. 9 This is a SEM image of a flat membrane cross section obtained by using a composite flat membrane brittle fracture device proposed by the present invention;

[0040] Fig.10 This is a SEM detail image of the flat membrane cross section obtained by a composite flat membrane brittle fracture device proposed in the present invention.

[0041] Numbers in the figure:

[0042] 1. Membrane fixing upper clamping plate; 2. Membrane fixing lower clamping plate; 3. Fixed end clamping component; 4. Fixing bolt; 5. Membrane placement area; 6. Membrane movable upper clamping plate; 7. Membrane movable lower clamping plate; 8. Movable end clamping component; 9. Movable bolt; 10. Front guide plate; 11. Rear guide plate; 12. Movable groove; 13. Membrane pollution layer; 14. Membrane skin layer; 15. Membrane pore layer; 16. Membrane support layer. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0044] like Figures 5 to 8 As shown, a composite flat membrane brittle fracture device provided by the present invention is suitable for brittle fracture of composite flat membranes, including a membrane fixing upper clamping plate 1, a membrane fixing lower clamping plate 2, a fixed end clamping component 3, a fixing bolt 4, a membrane placing area 5, a membrane movable upper clamping plate 6, a membrane movable lower clamping plate 7, a movable end clamping component 8, a movable bolt 9, a front guide plate 10, and a rear guide plate 11.

[0045] A horizontally arranged clamping mechanism is provided between the front guide rail plate 10 and the rear guide rail plate 11, and the clamping mechanism includes a fixed clamping device and a movable clamping device, a fixed clamping device, a film placement area 5 and a movable clamping device;

[0046] The fixed clamping device comprises a membrane fixed upper clamping plate 1 and a membrane fixed lower clamping plate 2, the membrane fixed upper clamping plate 1 and the membrane fixed lower clamping plate 2 are locked and connected by a fixed end clamping component 3 and connected to the front guide plate 10 and the rear guide plate 11 by a fixed bolt 4. The front guide plate 10 and the rear guide plate 11 are both provided with a penetrating movable groove 12, and the movable clamping device comprises a membrane movable upper clamping plate 6 and a membrane movable lower clamping plate 7, the membrane movable upper clamping plate 6 and the membrane movable lower clamping plate 7 are locked and connected by a movable end clamping component 8 and are arranged in the movable groove 12 between the front guide plate 10 and the rear guide plate 11 by a movable bolt 9;

[0047] The composite flat membrane is placed on the membrane placement area 5, and one end of the composite flat membrane is arranged between the membrane fixed upper clamping plate 1 and the membrane fixed lower clamping plate 2 and locked by the fixed end clamping component 3. The other end of the composite flat membrane is arranged between the membrane movable upper clamping plate 6 and the membrane movable lower clamping plate 7 and locked by the movable end clamping component 8. The movable bolt 9 connected to the movable clamping device is moved in the movable groove 12 on the front guide plate 10 and the rear guide plate 11 by the membrane movable upper clamping plate 6 and the membrane movable lower clamping plate 7 of the movable clamping device, thereby realizing the brittle fracture of the composite flat membrane.

[0048] Furthermore, the movable groove 12 on the guide plate 10 and the rear guide plate 11 provided by the present invention adopts an inverted L-shaped through-guide rail structure, and the L-shaped through-guide rail structure adopts a vertical guide rail to connect the horizontal guide rail, and the vertical guide rail adopts an arc-shaped transition to the horizontal guide rail; the movable clamping device is slidably set on the top of the vertical guide rail in the movable groove 12 of the front guide plate 10 and the rear guide plate 11 through the movable bolt 9.

[0049] The device used in the method will be described in detail below. It should be noted that the device diagram provided in this embodiment is for illustration only and does not limit its specific implementation form. Without departing from the concept of the present invention, several simple deductions or replacements can be made, which should be regarded as falling within the scope of protection of the present invention.

[0050] According to the above-mentioned brittle fracture device, the present invention provides a brittle fracture method of the brittle fracture device, comprising the following steps:

[0051] S1: Processing the composite flat membrane material into a long and thin strip, the width of which is slightly smaller than the width of the membrane placement area 5, and the processed length of the composite flat membrane material is slightly smaller than the length of the brittle fracture device;

[0052] S2: Place the membrane pollution layer 13 of the composite flat membrane upward above the membrane placement area 5, place one end of the composite flat membrane between the membrane fixed upper clamping plate 1 and the membrane fixed lower clamping plate 2 of the fixed clamping device in the brittle fracture device, and clamp it with the fixed end clamping component 3; place the other end of the composite flat membrane between the membrane movable upper clamping plate 6 and the membrane movable lower clamping plate 7 of the movable clamping device in the brittle fracture device, and clamp it with the movable end clamping component 8; fix the fixed clamping device between the front guide plate 10 and the rear guide plate 11 through the fixing bolt 4, and slide the movable clamping device through the movable bolt 9 to the top of the inverted L-shaped movable groove 12 of the guide rail through the front guide plate 10 and the rear guide plate 11, so that the movable clamping device can move in the plane direction between the front guide plate 10 and the rear guide plate 11, but is fixed in the direction perpendicular to the plane of the guide plate; during installation, the movable bolt 9 is in the same position in the guide rails of the two movable grooves 12 of the front guide plate 10 and the rear guide plate 11 and keeps the whole composite flat membrane in a straight state;

[0053] S3: immersing the composite flat membrane and the brittle fracture device as a whole in a cooling liquid to fully cool them;

[0054] S4: operate the brittle breaking device: separate the frozen composite flat membrane from the coolant after taking it out, quickly place the brittle breaking device on a horizontal surface, apply an operating force to the movable clamping device, that is, move the movable clamping device in the direction of the inverted L-shaped guide rail, first apply a steering force, and then apply a force in the horizontal direction, the movable clamping device moves in the movable groove 12 guide rail of the inverted L-shaped structure through the movable bolt 9;

[0055] S5: The frozen flat membrane material is made to fracture brittlely. At this time, two intact sections are formed at the junction of the lower clamping plate 2 for membrane fixing and the membrane placing area 5. The section above the membrane placing area 5 opposite to the upper clamping plate 1 for membrane fixing is the obtained clean section. These two sections are not in contact with and contaminated by other clamping plates and are not damaged by other forces. They are usable composite flat membrane sections.

[0056] Furthermore, the coolant used in step S3 of the present invention is liquid nitrogen, which has a boiling point of -196° C. at normal pressure, is inert, non-flammable and easily available.

[0057] Furthermore, the cooling time of the composite flat membrane in step S4 of the present invention in the cooling liquid is not less than 60 seconds to ensure that the composite flat membrane is fully cooled.

[0058] Furthermore, in step S4 of the present invention, the rotational operating force and the horizontal operating force are applied in sequence according to the direction of the guide rail by the brittle fracture device. The flat membrane material sample in step S5 has two potentially usable uncontaminated flat sections.

[0059] The following are embodiments provided by the present invention. The embodiments take the brittle fracture of a composite flat membrane material with a pollution layer and a non-woven fabric layer after a factory has been in operation for a period of time as an example, and further explain the function and effect of the present invention in conjunction with the accompanying drawings.

[0060] Example

[0061] The brittle fracture device of the present invention limits the operation direction and reduces the difficulty of operation, thereby preparing a cross section that can reflect the actual membrane and the longitudinal distribution of materials on the membrane surface. The preparation steps are as follows:

[0062] S1: Processing the flat membrane material into thin strips;

[0063] S2: placing the frozen composite flat membrane in a brittle fracture device and fixing it;

[0064] S3: immersing the composite flat membrane and the brittle fracture device in a cooling liquid to fully cool them to obtain a frozen composite flat membrane, and separating the frozen composite flat membrane from the cooling liquid;

[0065] S4: operating the brittle fracture device to sequentially apply forces from vertical to horizontal directions to the frozen flat membrane material;

[0066] S5: causing the frozen flat membrane material to fracture brittlely, thereby obtaining a brittle fracture flat membrane material sample.

[0067] Then from the SEM image and SEM detail image of the flat membrane cross section, it can be seen that the cross section is intact, there is no plastic deformation, the composite flat membrane has clear layers, and the image details are rich.

[0068] Comparing the samples of the composite flat membrane treated by the present invention with those treated by other methods, the samples have the following advantages:

[0069] 1. Apply horizontal and vertical forces to the flat membrane in sequence to reduce the influence of manual operation proficiency and randomness;

[0070] 2. The brittle fracture device provided by the present invention can generate two potentially usable cross sections;

[0071] 3. Compared with the existing brittle fracture method, the brittle fracture device provided by the present invention can more completely fracture the surface structure, and the obtained cross-section is more complete, the layers are clearer, the image details are richer, the deformation and damage are smaller, and the bending surface structure of the difficult brittle fracture represented by non-woven fabrics is retained.

[0072] In summary, the brittle fracture device provided by the present invention can limit the direction of the brittle fracture surface and obtain a smooth fracture surface. At the same time, it does not directly contact the brittle fracture surface, which can ensure that the fracture surface is not contaminated and stress-damaged, and reflects the actual structural characteristics.

[0073] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite flat membrane brittle fracture device, suitable for brittle fracture of composite flat membranes, characterized in that: include: A membrane fixing upper clamping plate (1), a membrane fixing lower clamping plate (2), a fixed end clamping component (3), a fixing bolt (4), a membrane placing area (5), a membrane movable upper clamping plate (6), a membrane movable lower clamping plate (7), a movable end clamping component (8), a movable bolt (9), a front guide plate (10), a rear guide plate (11) and a movable groove (12); A horizontally arranged clamping mechanism is provided between the front guide plate (10) and the rear guide plate (11), and the clamping mechanism comprises a fixed clamping device and a movable clamping device; the fixed clamping device connects the front guide plate (10) and the rear guide plate (11) via a fixed bolt (4); both the front guide plate (10) and the rear guide plate (11) are provided with a penetrating movable groove (12); the movable clamping device is arranged in the movable groove between the front guide plate (10) and the rear guide plate (11) via a movable bolt (9); the two ends of the composite flat membrane are respectively fixed in the fixed clamping device and the movable clamping device; by moving the movable clamping device, the movable bolt (9) connected to the movable clamping device moves in the movable groove (12) on the front guide plate (10) and the rear guide plate (11), thereby realizing a brittle fracture composite flat membrane.

2. The composite flat membrane brittle fracture device according to claim 1, characterized in that: The fixing clamping device comprises a membrane fixing upper clamping plate (1) and a membrane fixing lower clamping plate (2), wherein the membrane fixing upper clamping plate (1) and the membrane fixing lower clamping plate (2) are locked and connected via a fixed end clamping component (3); the end of the composite flat membrane is arranged between the membrane fixing upper clamping plate (1) and the membrane fixing lower clamping plate (2), and the membrane fixing upper clamping plate (1) and the membrane fixing lower clamping plate (2) are locked via the fixed end clamping component (3).

3. The composite flat membrane brittle fracture device according to claim 1, characterized in that: The movable clamping device comprises a membrane movable upper clamping plate (6) and a membrane movable lower clamping plate (7), and the membrane movable upper clamping plate (6) and the membrane movable lower clamping plate (7) are locked and connected via a movable end clamping component (8); The end of the composite flat membrane is arranged between a membrane movable upper clamping plate (6) and a membrane movable lower clamping plate (7), and the membrane movable upper clamping plate (6) and the membrane movable lower clamping plate (7) are locked by a movable end clamping component (8).

4. The composite flat membrane brittle fracture device according to claim 1, characterized in that: A film placement area (5) is provided between the fixed clamping device and the movable clamping device, the composite flat film is placed in the film placement area (5), and two ends of the composite flat film are respectively fixed in the fixed clamping device and the movable clamping device.

5. The composite flat membrane brittle fracture device according to claim 1, characterized in that: The movable grooves (12) on the front guide rail plate (10) and the rear guide rail plate (11) adopt an inverted L-shaped through-guide rail structure.

6. The composite flat membrane brittle fracture device according to claim 5, characterized in that: The inverted L-shaped through-guide rail structure of the movable groove (12) adopts a vertical guide rail to connect a horizontal guide rail, and the vertical guide rail adopts an arc-shaped transition to the horizontal guide rail; the movable clamping device is slidably arranged on the top of the vertical guide rail in the movable groove (12) of the front guide rail plate (10) and the rear guide rail plate (11) through a movable bolt (9).

7. A brittle fracture method for a composite flat membrane brittle fracture device according to any one of claims 1 to 6, characterized in that: The steps include: S1: Processing the composite flat membrane material into a thin and long strip, the width of which is slightly smaller than the width of the membrane placement area (5), and the processed length of the composite flat membrane material is slightly smaller than the length of the brittle fracture device; S2: The membrane contamination layer (12) of the composite flat membrane is placed upward above the membrane placement area (5); one end of the composite flat membrane is placed between the membrane fixed upper clamping plate (1) and the membrane fixed lower clamping plate (2) of the fixed clamping device in the brittle fracture device, and is clamped by a fixed end clamping component (3); the other end of the composite flat membrane is placed between the membrane movable upper clamping plate (6) and the membrane movable lower clamping plate (7) of the movable clamping device in the brittle fracture device, and is clamped by a movable end clamping component (8); the fixed clamping device is fixed between the front guide plate (10) and the rear guide plate (11) through a fixing bolt (4), and the movable clamping device is slidably set on the top of the inverted L-shaped movable groove (12) of the front guide plate (10) and the rear guide plate (11) through the movable bolt (9), so that the movable clamping device can move in the plane direction between the front guide plate (10) and the rear guide plate (11), but is fixed in the direction perpendicular to the plane of the guide plate; S3: immersing the composite flat membrane and the brittle fracture device as a whole in a cooling liquid to fully cool them; S4: operating the brittle breaking device: placing the brittle breaking device on a horizontal plane, applying an operating force to the movable clamping device, and the movable clamping device moves in the guide rail of the movable groove (12) of the inverted L-shaped structure through the movable bolt (9); S5: causing the frozen flat membrane material to fracture brittlely, thereby obtaining a brittle fracture flat membrane material sample, wherein the section above the membrane placement area (5) opposite to the membrane fixing clamp (1) is the obtained clean section.

8. The brittle fracture method of the composite flat membrane material according to claim 7, characterized in that: The cooling liquid used in step S3 is liquid nitrogen.

9. The brittle fracture method of the composite flat membrane material according to claim 7, characterized in that: The cooling time of the composite flat membrane in the cooling liquid in step S3 is not less than 60 seconds.

10. The brittle fracture method of the composite flat membrane material according to claim 7, characterized in that: In step S4, the rotational operating force and the horizontal operating force are applied in sequence according to the direction of the guide rail by the brittle breaking device.

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